FIG. 9 is a perspective view of an example of a conventional driver module structure and shows the main part of the driver module structure. The driver module structure of FIG. 9 is an example in which a large amount of heat is generated from a semiconductor device that controls a flat display or the like (see, e.g., Patent Document 1).
In FIG. 9, a driver module 30 includes a flexible circuit board 31 provided with a wiring pattern, semiconductor devices 32 connected to the flexible circuit board 31, and a heat-radiating member 34. In this configuration, the heat-radiating member 34 is joined to the back (upper portion) of each of the semiconductor devices 32. Thus, the heat generated from the semiconductor devices 32 is radiated into the surroundings via the heat-radiating member 34, and the semiconductor devices 32 are cooled.
For the conventional driver module structure of FIG. 9, the heat-radiating member 34 may be connected to a ground to suppress the effect of electromagnetic interference (EMI) on the semiconductor devices 32. In such a case, one end of a ground wire is connected to the heat-radiating member 34 with screws or the like and the other end is connected to a case that is a ground of an apparatus incorporating the driver module or a ground of the substrate, so that the heat-radiating member 34 can be shielded.
However, when the ground wire is used to connect the heat-radiating member 34 and the ground, the length of the ground wire becomes long. This increases the impedance for higher harmonics and reduces the effect of suppressing the EMI. Moreover, the ground wire itself may act as an antenna and generate harmonics.
Patent Document 1: JP 2000-299416 A